Drilling and installation system

Abstract

A system for drilling and simultaneously installing a relatively large production casing along an invert underground arcuate path beneath an obstacle is disclosed. A plurality of production casing segments, each having preformed curvature corresponding to the radius of the curvature of the arcuate path, are joined end to end and advanced along the desired path. A drill head is located in front of the leading end of the casing. The drill head is mounted to the casing so that the angular orientation of the drill head relative to the axis of the leading end of the casing is at least partially adjustable. A drill bit is located in front of the drill head and a motor is located within the drill head to drive the drill bit. The drill bit excavates a passageway along the arcuate path in advance of the casing. The angular orientation of the drill head relative to the axis of the leading end of the casing is controlled so that the passageway is excavated along the preselected arcuate path and the casing is simultaneously installed along that path.

What is claimed is: 
     
       1. Apparatus for drilling and simultaneously installing a relatively large production casing along an invert underground arcuate path beneath an obstacle from a first position at or near ground level on one side of the obstacle to a second position at or near ground level at the other side of the obstacle comprising: a plurality of production casing segments each having preformed curvature corresponding to the radius of curvature of said arcuate path, said casing segments adapted to be joined end to end to form a continuous production casing; means for advancing said casing along said path from said first position; a drill head located in front of the leading end of the casing; means for mounting the drill head to the casing so that the angular orientation of the drill head relative to the axis of the leading end of the casing is at least partially adjustable; a drill bit located in front of the drill head and mounted thereto; means within the drill head for driving the drill bit to excavate a passageway along said path in advance of the casing; and means for controlling the angular orientation of the drill head relative to the axis of the leading end of the casing so that the passageway is excavated along said path from said first position to a second position and the casing is installed therealong; a conduit for lubricating mud within the casing fluidly communicated to the exterior of the casing proximate the leading end thereof; and means for injecting lubricating mud through the lubricating mud conduit so that the lubricating mud is expelled proximate the leading end of the casing to lubricate the casing as it is advanced along the excavated passageway. 
     
     
       2. Apparatus as recited in claim 1 wherein said controlling means includes a plurality of hydraulic actuators spanning the mounting means from the casing to the drill head and disposed circumferentially about the casing and the drill head, and means for extending and contracting the actuators to control the angular orientation of the drill head relative to the axis of the leading end of the production casing. 
     
     
       3. Apparatus as recited in claim 1 wherein said driving means comprises a hydraulic motor located within the drill head and adapted to power the drill bit; and additionally comprising a supply conduit for drilling mud passing through the interior of the casing and connected with the hydraulic motor to supply drilling mud to and thereby use the drilling mud to drive the hydraulic motor, said used drilling mud being expelled at the drill bit to entrain cuttings from the excavated passageway and means for collecting the drilling mud and entrained cuttings at the drill head and impelling the drilling mud and entrained cuttings under positive pressure rearwardly out of the casing. 
     
     
       4. Apparatus as recited in claim 1 and additionally comprising a conduit for lubricating mud within the casing fluidly communicated to the exterior of the casing proximate the leading end thereof; and means for injecting lubricating mud through the lubricating mud conduit so that the lubricating mud is expelled proximate the leading end of the casing to lubricate the casing as it is advanced along the excavated passageway. 
     
     
       5. Apparatus according to claim 1 and wherein said drill head excavates a diameter greater than the diameter of said casing. 
     
     
       6. The apparatus of claim 1 and including a seal between said drill bit and said conduit for lubricating mud for isolating said lubricating mud from said drill bit. 
     
     
       7. A method for emplacing a casing beneath an obstacle between first and second locations at or near ground level comprising the steps of excavating a passageway in liquid premeated soil formations having a preselected diameter along an invert arcuate path having a generally constant radius of curvature under said obstacle between said locations; providing a plurality of casing segments each having a preformed radius of curvature corresponding to the radius of curvature of the arcuate path; joining said casing segments end to end to form a continuous curved casing; introducing a transport fluid at the site of said excavating; entraining the cuttings from said excavating in the transport fluid; nonrotatably advancing said casing into and along the arcuate path of said passageway; collecting said transport fluid and entrained cuttings in the interior of the leading portion of said casing; evacuating the transport fluid and entrained cuttings under positive pressure from the interior of the leading portion of said casing to prevent the cuttings from settling in the ground circumscribing the advancing casing; sealing off the interior of said casing proximate the leading portion thereof to provide buoyancy to the casing within the passageway; and weighting the casing to substantially neutralize said buoyancy to minimize friction between the casing and the sidewalls of the passageway to facilitate advancement of said casing into the passageway. 
     
     
       8. A method according to claim 7 wherein said excavating step comprises drilling the passageway with a drill located in front of the casing. 
     
     
       9. A method according to claim 7 wherein the diameter of the passageway is greater than the diameter of the casing, and additionally comprising the step of injecting lubricating mud into the annular void between the casing and the sidewalls of the passageway to lubricate the casing as it moves along the passageway.